[ninicraftone]

Are you plugging the kobo directly into the computer or is there a usb hub that you are using? My sister has a kobo / usb / computer arrangement that won't work to mount the kobo. She has to unplug the usb hub and plug the kobo directly into the computer. I have no idea why.

Also, I have occasionally had trouble with various external drives not mounting correctly and have solved the problem by assigning a drive letter manually by right clicking the computer icon on the desktop, choosing 'manage', then 'storage' > 'disk management', right click on the drive if you see it listed and 'change drive letters and paths'. If you don't see the drive try 'rescan' under 'action' on the toolbar. That has worked for me in the past (not for a kobo but for other usb drives that would not mount).

I hope one of these suggestions helps.